Arranging equipment to produce a variety of parts
June 12, 2007
To stay competitive, stampers must be prepared to run a variety of dies, many of which have been designed to run on customized and complex OEM equipment. In addition, stamping concepts tend to differ among the automotive OEMs. For the tier stamper, flexibility is key to surviving these fiercely competitive times.
The influx of European and Asian automotive manufacturers into the North American market, along with increased outsourcing of stamped parts, is creating both opportunities and challenges for the tier and general stamping industry.
To stay competitive, North American stampers must be prepared to run a variety of dies, many of which have been designed to run on customized and complex OEM equipment. In addition, stamping concepts tend to differ among the automotive OEMs. For the tier stamper, flexibility is key to surviving these fiercely competitive times.
As automotive OEMs continue to outsource a wider variety of parts to tier stampers, flexibility is increasingly important—from the ability to form many different parts to having alternative capacity to minimize downtime. It's a challenge to own all the equipment needed to handle the widest array of parts, but doing so ensures continuous orders, as well as growth and profitability.
North American tier stampers operate predominantly with progressive-die and transfer presses. Progressive-die presses typically are used for small structural parts and are fed by coil feed lines. Transfer presses make large parts, which require additional tonnage and larger beds.
It is common for coil feed lines or destackers to feed transfer presses. If a coil feed line is used, blanks are cut and drawn in the first die station, and a transfer system moves blanks to the following die stations.
If a destacker is used, blanks are cut and stacked in dedicated blanking systems. If blanks are supplied by a steel service center, they are fed to the transfer press later on. In some cases, Class A parts can be manufactured in transfer presses fed by a destacker.
Along with having equipment flexibility inside the shop, managers in the tier market must consider other business challenges that influence production flexibility. Constant pressure from OEMs to reduce piece price, limited operator skills, and a reduced maintenance staff are some common examples. These pressures are driving equipment manufacturers to design low-maintenance, high-reliability, and user- friendly stamping equipment.
Balancing equipment automation with required production rates also is a challenge. Overly complex press systems directly affect the level of operator skill and training required. All of these factors have an impact on return on investment, which relies heavily on the careful balance between press system expense and productivity to generate a healthy return.
Engineering advancements are fostering a combination of progressive and transfer press concepts to improve the equipment's ability to produce a variety of parts. The goal is to devise one press system that provides the high speed of a progressive-die press with the transfer press's capability to process large parts.
One option for press flexibility is to arrange two destacker carts in tandem with the press. The feeder moves in and out on the same rails as the destacker cart positioned closer to the press.
Tier stampers and press system engineers are developing creative solutions to meet the need for flexibility. One concept is installing a coil feed line in addition to a destacker, with the option of either piece of equipment feeding the same press. For parts that require transfer dies, the press can be fed by either a coil feed line or a destacker. For parts that require progressive dies, the press is fed by a coil feed line.
Several different configurations can create system flexibility. For example, both a coil feed line and a destacker can be installed on a press's entry side, which provides two options for moving the feeder in and out of operating position.
One option is to arrange two destacker carts in tandem with the press. The feeder moves in and out on the same rails as the destacker cart positioned closer to the press. In this case, production rates using blanks from the destacker cart positioned farther from the press will be slightly lower than from a cart positioned closer to the press (see Figure 1).
Another option is side-by-side destacker carts. Production rates using the destacker will be the same, because both carts use the same set of rails. The feeder moves into working position by rolling on rails placed transverse to the destacker carts, and it can be moved away from the press on a bridge that extends over the loop area.
A second option is to position destacker carts side by side. In this case, part production rates using the destacker will be the same, because both carts use the same set of rails. The feeder moves into working position by rolling on rails placed transverse to the destacker carts, and it can be moved away from the press on a bridge that extends over the loop area (see Figure 2).
Both configurations can run a variety of parts, no matter how the system is fed or how the die is designed.
Another example of a flexible system configuration operating in commercial production is the coil feed line on one side of the press and the destacker on the other side. In this case, both systems are mounted in fixed positions.
The system's exit conveyor must be on wheels so it can be moved and positioned on both sides of the press. Depending on which piece of equipment feeds the press, the exit conveyor must be placed accordingly. It should be noted that the transfer system must be fully programmable to allow parts to move in both directions inside the dies (see Figure 3).
In this configuration, the system's exit conveyor is on wheels so it can be moved and positioned on both sides of the press. Depending on which piece of equipment feeds the press, the exit conveyor can be placed accordingly.
While industry consultants predict more outsourcing of stamped parts and consolidation among the tier suppliers, strategic positioning is key to staying competitive. A proactive approach to developing flexible stamping facilities can be the springboard to differentiate a shop, as it allows a depth of product range and can provide production backup with the ability to interchange dies and production between different press systems.
The ability to differentiate with system flexibility can lead to customer and product diversification, which supports the goal of productivity and a strong balance sheet.